T. Yamato et al., SYNTHESIS AND ION SELECTIVITY OF MACROCYCLIC METACYCLOPHANES ANALOGOUS TO SPHERAND-TYPE CALIXARENES, Journal of inclusion phenomena and molecular recognition in chemistry, 19(1-4), 1994, pp. 315-331
Novel macrocyclic compounds, hexahydroxy[1.0.1.0.1.0]- (2b) and octahy
droxy[1.0.1.0-1.0.1.0]metacyclophane (2c) have been prepared in 50-70%
yield by base-catalyzed condensation of 5,5'-di-tert-butyl-2,2'-dihyd
roxybipheny (1) with formaldehyde in refluxing xylene. An attempted al
kylation of the flexible macrocycles 2b and 2c with ethyl bromoacetate
in the presence of Cs2CO3 under acetonitrile reflux gave only one pur
e stereoisomer 3 and 4, respectively, while other possible isomers wer
e not observed. The structural characterization of these products is a
lso discussed. The two-phase solvent extraction data indicated that he
xaethyl ester 3 and octaethyl ester 4 show strong metal affinity, comp
arable with that of the corresponding calix[n]arenes, and a high K+ se
lectivity was observed for octaethyl ester 4. H-1-NMR titration of hex
aethyl ester 3 and octaethyl ester 4 with KSCN clearly demonstrate tha
t a 1 : 1 complex is formed which is stable on the NMR time scale.